This invention relates to a digital audio signal error correction circuit, and more particularly to an error correction circuit for a digital audio signal that is reproduced by a tape recording/reproducing apparatus.
In a digital video tape recording/reproducing apparatus (VTR), video and audio signals are converted into digital signals and then recorded on a magnetic tape. In particular, the audio signal is converted into PCM data, and, after the time axis of the PCM data is compressed, a parity code for subsequent error detection is added. The time-compressed audio data is then inserted into the vertical blanking period and is thereafter recorded. In this case, the same audio data is recorded twice in order to ensure a higher-fidelity reproduction, even if one of the audio data is not reproduced due to drop out. If at least one data of the twice recorded data is reproduced completely during the reproduction, the audio data can be reproduced without error. When both recorded data are not reproduced due to drop out in a certain short time period, data corresponding to the lost data is produced by interpolation if two data before and after the drop out portion are normally reproduced. When twice recorded data are lost for a long period, a preceding data is held, and when the loss of the data lasts further, a mute state is provided.
A prior art error correction circuit has the problem that if there is a large difference in level between newly reproduced data and the held data or the muting data, an offensive click noise is produced when the data-holding state or the muting state returns to the normal state.